This invention relates generally to draft inducers for hot water heaters. More particularly, the present invention relates to blower designs for cooling and expelling heated flue gases emanating from conventional hot water heaters.
The water heater has been around for many years to provide a supply of heated water for both commercial and consumer usage. To generate the requisite thermal energy needed to increase the temperature of the water therein, a gas or oil fired burner is commonly employed. The burner produces hot combustion gases (flue gases) that need to be drawn through the flue of the water heater via the most rigorous path allowable in order to minimize heat losses and maximize the overall efficiency of the water heater.
To move the gases through the water heater, centrifugal blowers were engineered into the system. This allowed the most rigorous path possible for the flue, which in turn increased the amount of heat transferred from the flue gases to the water. An additional benefit of the use of a blower with a water heater was that the temperatures of the exhaust gases exiting the flue were reduced due to more efficient heat scrubbing. However, in naturally aspirated water heaters, the gases exiting the water heater were still extremely hot. This required the use of steel exhaust tubing, which needed to be vented to the outside of the structure in a nearly vertical manner for safety. By using a blower, the temperatures of the exhaust gases were reduced to the point that a wider array of materials became available for exhaust piping. Specifically, this allowed for the safe use of PVC piping and horizontal venting through the nearest wall to vent the exhaust gases to the outside atmosphere.
However, the utilization of a blower in conjunction with a water heater presented several challenges. The exhaust gases in the flue, while much lower in temperature than normally aspirated water heaters, were still above ideal temperatures for direct venting through PVC piping. To achieve desirable temperature levels, dilution (cooling) air at ambient temperature was introduced into the system and mixed with the hot exhaust gases from the flue. Hence, the complexity and expense of the blower assisted water heater was introduced when exhaust gases were mixed with the dilution air.
Attention is drawn to a solution for adding dilution air to exhaust gases, which employed intricate plumbing layouts that increased manufacturing costs and increased potential failure sources through the myriad of connections. This solution involved the use of a T-connection attached to the flue with dilution air being drawn through the connection along with the hot exhaust gases. The entire blower assembly required multiple tubes, connections and other heat resistant components to direct the exhaust gases and dilution air through and out of the water heater/blower system.
An additional problem surrounding this solution was that exhaust fumes could potentially make contact with the blower motor thereby causing the blower motor to overheat, which affected the longevity of the motor and overall efficiency of the blower unit. Additionally, exhaust gases contacting the motor were able to leak into the ambient thereby creating various health risks due to the toxicity of the exhaust fumes.
The instant invention solves many of the problems with the plumbing and mixing of the hot exhaust gases with dilution air. Additionally, the instant invention reduces production and maintenance costs while increasing the overall safety, efficiency and durability of the water heater blower assembly.
The present invention provides an improved motor blower assembly as described herein. Said motor blower assembly, or dilution air blower, includes a blower housing that mounts and seals to a conventional hot water heater and is sized to fit between the heater""s inlet and outlet water pipes. Said blower housing is vented in order to draw dilution air into the blower unit to cool the flue gases expelled from the water heater.
The one-piece blower housing has three apertures on its top surface to receive bolts to secure a conventional motor to the blower housing, and one radially centered aperture to receive the motor shaft. The blower housing has portions defining a first chamber for receiving an impeller. The impeller is fixed to a motor shaft attached to the rotor of a motor. Additionally, the housing has portions which define an exhaust outlet that is in fluid communication with the first chamber. The outlet provides egress for exhaust gases emanating from a hot water heater to which the blower is attached.
A blower housing cover or inlet plate is provided which is attached to the blower housing at an intermediate location along the sidewall of the blower housing. The inlet plate has an inlet opening to allow dilution air and exhaust gases from a hot water heater to enter the first chamber.
The sidewall of the blower housing extends beyond the inlet plate and forms a first and second skirt. The blower housing is vented through the provision of at least one vent opening or slot disposed within the second skirt. Both the first and second skirt have portions defining a flange adapted for securing the blower housing to the top of a hot water heater. The combination of the lower portion of the housing sidewall, the first and second skirt, the inlet plate, and the top of the water heater form a second chamber within which a flue pipe of the hot water heater is confined. The second chamber is in fluid communication with the first chamber via the inlet aperture of the inlet plate.
When the impeller is rotated, a negative pressure is created in the first chamber. This negative pressure draws dilution air through the at least one vent slot or opening in the skirt section of the housing, and draws exhaust gases from the hot water heater. The dilution air mixes with the hot exhaust gases in the second chamber, which significantly reduces the temperature of the gases to an acceptable level for expulsion. The gas/air mixture is then drawn into the first chamber where it is forced through the outlet portion of the blower housing.